EXOTICS
Setting up the Right Stimulation
Mice
Most of the research that assesses environmental
enrichment strategies in laboratory animal medicine
focuses on the mouse. Studies have evaluated how
a mouse interacts with its environment and with a
variety of strategies to determine how to improve its
well-being. Combined with an evaluation of the natural
history of this species, the prevailing strategies involve
interventions that mimic the natural environment.
Mice thrive when provided with a complicated space,
created with multi-level caging or the use of cage
furniture, which recreates an environment similar to
the burrows where their wild counterparts live. They
also preferentially select and actively engage with
nesting materials formulated from a combination of
long strips of paper and softer cloths that allow them to
make complicated nests where they can comfortably
sleep and maintain their preferred body temperatures.
These interventions are simple to implement in most
mouse caging and provide significant improvements
to animal well-being.
Community Living
Often, one of the simplest ways to enrich a rodent is to
establish group housing. Rats, gerbils and guinea pigs
tend to generally get along well with one another and
preferentially select group housing when given the
opportunity. A little more caution is required with male
mice and female hamsters because some individuals
of these species tend to fight when socially housed.
Rats
Extrapolating these results to other small mammals
can be us eful but needs to be done with caution and
an eye to ensuring that the desired results have been
achieved. For example, though mice universally enjoy
engaging in nest-building behavior, this behaviour is
much more strain-dependent for rats. A common
albino rat, the Sprague Dawley, seems to benefit
from the provision of nesting material, but its hooded
cousin—the fancy rat, which is most commonly seen
as a pet—does not interact with nesting material in
a constructive manner. In general, rats benefit from
the provision of complex environments that allow
them to climb, explore and maintain normal postural
adjustments, including rearing on the hind limbs.
Gerbils
Gerbils benefit from toys, running wheels and cage
furniture and substrates that encourage digging and
burrowing, allowing this species to more fully engage
in their very active species-specific behaviours.
Hamsters
Hamsters enjoy digging and burrowing, so they benefit
from the provision of deep bedding and shelters.
Nutrition Nuggets for All.
All of these species also benefit from the provision of
wood or plastic materials that allow them to gnaw,
assisting them in proper care of their continuously
growing incisors. Their food is typically provided as an
extruded block, which also wears down the incisors.
Although other treats, such as sunflower seeds, can
be provided for foraging enrichment, the amount of
these treats should be controlled to prevent obesity
and malocclusion problems.
Rabbits and Guinea Pigs
Original recommendations for rabbit and guinea pig
care included an all-pelleted diet and chew toys. The
current norm is to provide them with a diet primarily
based on a grass hay (e.g. Timothy hay) supplemented
by pellets. Enrichment should also be focused on
their natural behavioural needs for security or hiding
and continual grazing. Female rabbits will only build
immediately before kindling, while guinea pigs do not
create nests at all, but both species benefit from the
provision of houses in which they can hide. Guinea
pigs also enjoy the ability to move to, and circle, the
perimeter of their cage.
Since both species need to wear down their incisors,
structural items that are also edible are preferred.
Additionally, nonedible items (e.g. items made of an
appropriate hard plastic) that provide hiding spaces but
do not pose a hazard after continual wear and can be
easily sanitised are also preferred. Items that present
hazards, such as sharp edges or holes big enough
for teeth to get stuck in, should not be purchased
for rabbits and guinea pigs. Items that become worn
over time should eventually be discarded if a hazard
becomes apparent or it cannot be kept clean.
Sugary or carbohydrate-based treats must be avoided
as this will disrupt their gut metabolism. Many clients
are still drawn to treats and toys that they themselves
would want to have, so client education is key in order
for them to understand what is best nutritionally and
behaviorally for rabbits and guinea pigs.
Exercise your expertise
Veterinarians are now able to provide species-specific
advice and guidance to clients based on recent
research and advances focused on making the lives
of small mammal pets better. As their population in
the pet realm continues to increase, this will help
ensure that veterinarians remain a primary source of
information for the owners for these cute and fun
pets.
*Stacy Pritt, DVM, MS, MBA, CPIA, DACAW, is the Director
of the Institutional Animal Care and Use Committee Office
at the University of Texas Southwestern Medical Center
and the current vice president of the American Veterinary
Medical Association. Debra Hickman, DVM, MS, DACLAM,
DACAW, is the Attending Veterinarian for the School of Wound
Management Medicine at Indiana University, Indianapolis. She
also has an active research lab that evaluates interventions to
improve the well-being of animals used in research. Both Drs.
Pritt and Hickman have won numerous awards for training and
research.
Issue 01 | MARCH 2018 | 9